Improved method of applying gutta percha to a carrier

Abstract: The present invention is an improved method and device used in applying gutta percha to a carrier which will later be used in filling and sealing an interior of a tooth after a root canal has been performed on the tooth. The method consists of inserting gutta percha filled cannula 28 into the barrel cavity 24 of a syringe-type device 10, heating the cannula in order to increase the plasticity of the gutta percha, inserting a carrier 14 into the cannula at the dispensing end of the syringe-type device and pushing a plunger 34 of the syringe-type device downward in order to push the carrier, which is now coated with the gutta percha previously contained in the cannula, out of the dispensing end of the cannula. The gutta percha coated carrier is then ready for use in the root canal. An alternate embodiment of the syringe-type device employs a modified plunger to accommodate an alternate cannula which is provided with its own dispensing cannula plunger.

Description: Background Of The Invention 1. Field Of The Invention The present Invention relates generally to the field of endodontics and more specifically to a method for preparing a gutta percha coated carrier used in obturating an extirpated root canal. 2. Description Of The Related Art Current methods of obturating (filling) an extirpated (stripped) root canal commonly involve packing a root canal with a thermoplastic material, such as gutta percha, so that the root canal space is filled with the thermoplastic material. Preferably, the space is filled with the thermoplastic material forming a seal which prevents leakage between the root canal and the surrounding tissue. It has been found that a satisfactory seal can be formed by softening the gutta percha by heating it prior to inserting it into the root canal. Normally, the gutta percha is applied to a carrier prior to insertion into the root canal in order to facilitate insertion. Carriers precoated with gutta percha are known, as shown by U.S. Patent No. 4,758,156 issued on July 19,1988 to the inventor of the present invention. However, carriers pre-coated with gutta percha are expensive to purchase, and a less expensive means is desired for applying gutta percha to a carrier. U.S. Patent 5,067,900 issued November 26, 1991 to inventor, McSpadden, teaches an inexpensive method of applying gutta percha to a carrier. The McSpadden patent teaches use of a syringe whose barrel is pre-filled with sufficient gutta percha to coat a plurality of carriers. According to the teachings of McSpadden, the amount of gutta percha applied to a carrier is dependent on the force exerted on the plunger of the syringe and upon the rate of withdrawal of the coated carrier from the discharge end of the syringe. One problem with this method is that the person coating the carrier must be steady-handed in order to obtain a uniform and consistent coating of the carrier. Steady handiness is difficult with the McSpadden device since the entire syringe body is hot due to the preheating necessary to increase the plasticity of the gutta percha. Also, another problem with multiple usage syringes, such as the McSpadden syringe, which forms the basis for the preamble of claim 6, is that if the carrier is inserted into the root canal to test the sizing fit prior to applying the gutta percha to the carrier, as is the common practice, it may be coated with debris that could contaminate the community pool of gutta percha of the syringe. WO-A-9216174 discloses a method and a device for applying gutta percha to a carrier. The device comprises a barrel containing a quantity of gutta percha. The carrier may be inserted through an orifice of the barrel into the gutta percha, and a quantity of gutta percha may be extruded from the barrel onto the carrier by means of a movable plunger. US-A-3,744,493 discloses a reusable pellet implanter, which comprises a tubular body having a movable plunger therein. A pellet cartridge, which comprises a number of pellets arranged one after another, may be inserted into the tubular body via a side breech opening until an upper open end of the pellet cartridge is secured in the tubular body. By pushing the movable plunger, the pellets may be implanted under the skin of an animal being treated. The present invention provides a reliable, easy to use, and inexpensive method for applying a uniform coating of gutta percha to a carrier without contamination problems, as it employs a single dosage, disposable source of gutta percha. Summary Of The invention Briefly, the present invention is a method and a syringe-type device for applying gutta percha to a carrier which will later be employed to obturate an extirpated root canal. The steps of the method consist of: (1) inserting a cannula filled with a measured amount of gutta percha into a barrel cavity provided in a barrel of the syringe-type device so that an upper lip provided on the cannula seats in a mating reduced diameter section of the barrel cavity, (2) applying heat to the cannula to increase the plasticity of the gutta percha, (3) inserting a carrier into a lower open end of the cannula, and (4) pushing a plunger provided in the device downward by means of a ring attached to an upper end of the plunger and by means of finger tabs provided on a plunger insertion end of the barrel so that a reduced cylindrical portion of the plunger provided on a lower end of the plunger enters an upper open end of the cannula and pushes the carrier, to which the gutta percha is now applied, out of the lower open end of the cannula and out of the device at its dispensing end. The barrel is provided with an insulating sleeve to prevent fingers from contacting the heated barrel as the fingers push the plunger downward. Alternately, the device may be modified by replacing the plunger with an alternate plunger designed to accommodate an alternate cannula which is provided with its own attached dispensing cannula plunger. In this alternate embodiment, the alternate plunger is pushed downward against the dispensing cannula plunger and the dispensing cannula plunger is pushed from the alternate cannula's upper open end to its lower open end, thus pushing the gutta percha coated carrier out of the lower open end of the alternate cannula and out of the dispensing end of the device. Brief Description Of The Drawings Figure 1 is a front elevation of the device for applying gutta percha to a carrier according to a preferred embodiment of the present invention, showing a carrier inserted into the dispensing end of the device. Figure 2 is a front elevation of the device of Figure 1 showing the gutta percha coated carrier after it is pushed out of the dispensing end of the device. Figure 3 is an enlarged partial front elevation of the device for applying gutta percha to a carrier according to another embodiment of the present invention, showing a gutta percha containing alternate cannula provided with its own cannula plunger. Figure 4 is a slightly enlarged front elevation of a plunger removed from the device of Figure 1. Figure 5 is a top plan elevation of the plunger of Figure 4. Figure 6 is a slightly enlarged front elevation of a barrel removed from the device of Figure 1. Figure 7 is a top plan elevation of the barrel of Figure 6. Figure 8 is a left side elevation of the barrel of Figure 6. Figure 9 is a front elevation of a gutta percha containing cannula for use with the device of Figure 1. Figure 10 is a cross-sectional view of the cannula taken along line 10-10 of Figure 9. Figure 11 is a left side elevation of the barrel illustrating insertion of the cannula into the barrel via a side opening provided in the barrel. Figure 12 is a left side elevation of the barrel illustrating the cannula being heated after it is inserted into the barrel. Figure 13 is a front elevation of a second alternate embodiment of the device for applying gutta percha to a carrier according to the present invention, shown loaded with a cannula of gutta percha. Figure 14 is a front elevation of a second alternate barrel removed from the device of Figure 13 showing the cannula being loaded therein. Figure 15 is a top plan view of the second alternate barrel taken along line 15-15 of Figure 14. Figure 16 is a front elevation of a second alternate plunger removed from the device of Figure 13. Figure 17 is a top plan view of the second alternate plunger of Figure 16. Figure 18 is a left side elevation of the second alternate barrel illustrating the cannula being heated after it is loaded into the second alternate barrel. Figure 19 is a partial front elevation of the device of Figure 13, showing a carrier inserted into the dispensing end of the device. Figure 20 is the device of Figure 19, showing the gutta percha coated carrier after it is pushed out of the dispensing end of the device. Detailed Description Of The Preferred Embodiments Referring now to the drawings and initially to Figures 1 and 2, there is illustrated a syringe-type device 10 for applying gutta percha 12 or other suitable thermoplastic material (not illustrated) to a carrier 14 according to a preferred embodiment of the present invention. The device 10 is provided with a barrel 16, illustrated in Figures 6, 7, and 8, having a plunger insertion end 18 and an opposite dispensing end 20. Adjacent the plunger insertion end 18, the barrel 16 is provided externally with an insulating sleeve 21 which prevents fingers (not illustrated) from contacting the barrel 16 after the barrel 16 is heated, as will be described more fully hereinafter. The plunger insertion end 18 is also provided with a pair of outward extending finger tabs 22, one finger tab 22 being provided on either side of the barrel 16. A barrel cavity 24 communicates between the plunger insertion end 18 and the dispensing end 20. Adjacent the dispensing end 20, the barrel 16 is provided with an opening 26 which communicates with the barrel cavity 24. As illustrated in Figures 9, 10 and 11, a cannula 28 pre-filled with gutta percha 12 inserts into the barrel cavity 24 by way of opening 26. The cannula 28 is provided with an upper open end 29 and an opposite lower open end 31 and is hollow between the upper and lower open ends 29 and 31. The gutta percha 12 is pre-filled in the hollow cannula 28 between the upper and lower ends 29 and 31. Once inserted into the barrel cavity 24, the cannula 28 is pushed toward the dispensing end 20 until an upper lip 30 provided on the cannula 28 seats into a mating reduced diameter section 32, best seen in Figures 6 and 8, provided in the barrel cavity 24. The reduced diameter section 32 is located so that when the cannula 28 is seated therein, the open lower end 31 of the cannula 28 is approximately flush with the dispensing end 20. As shown in Figure 12, once the cannula 28 is seated in the reduced diameter section 32, the gutta percha 12 is then heated by means of a flame 33 or other suitable heat source (not illustrated) in order to increase the plasticity of the gutta percha 12 in preparation for inserting it into a root canal (not illustrated). The device 10 is preferably constructed of metal or other suitable material to enable the device to withstand heating of the gutta percha 12 when the cannula 28 is contained therein As illustrated in Figures 1, 4, and 5, the device 10 is provided with a plunger 34 having an upper end 36 and an opposite lower end 38. The upper end 36 is provided with a ring 40 which attaches to one end of a cylindrical main body 42 provided on the plunger 34. The main body 42 attaches by an opposite end to a reduced cylindrical portion 44 which forms the lower end 38. The cylindrical main body 42 has an outside diameter slightly smaller than an inside diameter of the barrel cavity 24, and the reduced cylindrical portion 44 has an outside diameter slightly smaller than an inside diameter of the cannula 28. The lower end 38 of the plunger 34 inserts into the barrel cavity 24 at the plunger insertion end 18 of the barrel 16, and the plunger 34 moves downward in the barrel cavity 24 until the lower end 38 touches the heated gutta percha 12 contained within the cannula 28. Movement of the plunger 34 is facilitated by inserting a thumb (not illustrated) into the ring 40 and placing middle and index fingers (not illustrated) of the same hand (not illustrated) as the thumb (not illustrated) under the finger tabs 22 and pressing the fingers (not illustrated) toward the thumb (not illustrated). As illustrated in Figures 1 and 2, a carrier 14 is then inserted into the heated cannula 28 via the dispensing end 20. The plunger 34 is then pushed downward, thus pushing the carrier 14, which is now coated with gutta percha 12, out of the device 10. The carrier 14 is then ready for use in a root canal (not illustrated). An alternate device 10A is illustrated in Figure 3. This embodiment is used in conjunction with an alternate cannula 28A which is provided with its own dispensing cannula plunger 46. In this embodiment, the barrel 16 is employed and an alternate plunger 34A is used which is identical to the plunger 34 except that the reduced cylindrical portion 44 is eliminated. Similar to the first embodiment, the alternate cannula 28A is inserted into the barrel 16 and is heated. Thereafter, the alternate plunger 34A is inserted into the barrel cavity 24 and pushed downward until the alternate plunger 34A engages the dispensing cannula plunger 46. At this point, a carrier 14 is inserted into the heated cannula 28A via the dispensing end 20. The alternate plunger 34A is then pushed downward, thus pushing the dispensing cannula plunger 46 downward through the alternate cannula 28A and pushing the carrier 14, which is now coated with gutta percha 12, out of the alternate device 10A. The carrier 14 is then ready for use in a root canal (not illustrated). A second alternate device 10B is illustrated in Figures 13 through 20. This embodiment is provided with an alternate barrel 16B, illustrated in Figures 14 and 15. The alternate barrel 16B has an alternate plunger insertion end 18B and an opposite alternate dispensing end 20B. Adjacent the alternate plunger insertion end 18B, the alternate barrel 16B is provided externally with an alternate insulating sleeve 21B similar to the insulating sleeve 21 described for the first embodiment of the device 10. The alternate plunger insertion end 18B is likewise provided with a pair of outwardly extending alternate finger tabs 22B, one alternate finger tab 22B being provided on either side of the alternate barrel 16B. An alternate barrel cavity 24B communicates between the alternate plunger insertion end 18B and the alternate dispensing end 20B. The alternate barrel cavity 24B is provided with an alternate mating reduced diameter section 32B at the alternate dispensing end 20B, with the remaining length of the alternate barrel cavity 24B being uniform in internal diameter. As illustrated in Figure 14, a second alternate cannula 28B, pre-filled with gutta percha 12 between its second alternate cannula open upper end 29B and its opposite second alternate cannula lower end 31B, is inserted into the alternate barrel insertion end 18B of the alternate barrel cavity 24B. The second alternate cannula 28B is then pushed toward the alternate dispensing end 20B until the second alternate cannula open lower end 31B extends outward from the alternate dispensing end 20B and the second alternate cannula 28B is secured by an alternate upper lip 30B provided on the second alternate cannula open upper end 29B which seats into the alternate mating reduced diameter section 32B of the alternate barrel cavity 24B. As shown in Figure 18, once the second alternate cannula 28B is seated in the alternate mating reduced diameter section 32B, the gutta percha 12 is heated by means of the flame 33 or other suitable heat source (not illustrated) in order to increase the plasticity of the gutta percha 12 in preparation for inserting a carrier 14 into the second alternate cannula 28B. The second alternate device 10B, although not directly heated by the flame 33 in this embodiment, is preferably constructed of metal or other suitable material to enable the second alternate device 10B to withstand heat transferred to it by means of the attached alternate cannula 28B as it is heated. As illustrated in Figures 16 and 17, the second alternate device 10B is provided with a second alternate plunger 34B having an alternate upper end 36B and an opposite alternate lower end 38B. The alternate upper end 36B is provided with an alternate ring 40B which attaches to one end of an alternate cylindrical main body 42B provided on the second alternate plunger 34B. The alternate cylindrical main body 42B attaches by an opposite end to an alternate reduced cylindrical portion 44B which forms the alternate lower end 38B. The alternate cylindrical main body 42B has an outside diameter smaller than an inside diameter of the alternate barrel cavity 24B, and the alternate reduced cylindrical portion 44B has an outside diameter slightly smaller than an inside diameter of the second alternate cannula 28B. The alternate cylindrical main body 42B is provided with circumferential groove 48 therearound into which an O-ring 50 inserts. As the alternate cylindrical main body 42B is pushed through the alternate barrel cavity 24B and the alternate reduced cylindrical portion 44B is simultaneously pushed through the second alternate cannula 28B, the O-ring 50 movably engages the alternate barrel cavity 24B. The purpose of the O-ring 50 is to provide frictional resistance to movement of the second alternate plunger 34B within the alternate barrel 16B and thereby enabling the user to more precisely control movement of the second alternate plunger 34B. After the second alternate cannula 28B is heated, the second alternate plunger 34B is inserted into the alternate barrel 16B at the alternate plunger insertion end 18B and is moved downward into the alternate barrel cavity 24B until the alternate lower end 38B touches the heated gutta percha 12 contained with the second alternate cannula 28B. Movement of the second alternate plunger 34B is facilitated by inserting a thumb (not illustrated) into the alternate ring 40B and placing middle and index fingers (not illustrated) of the same hand (not illustrated) as the thumb (not illustrated) under the alternate finger tabs 22B and pressing the fingers (not illustrated) toward the thumb (not illustrated). As shown in Figure 19, the carrier 14 is then inserted into the heated second alternate cannula 28B via the second alternate cannula open lower end 31B. As shown in Figure 20, the second alternate plunger 34B is then pushed downward, thus pushing the carrier 14, which is now coated with gutta percha 12, out of the second alternate device 10B. The coated carrier 14 is then ready for use in a root canal (not illustrated). Although not illustrated, the second alternate device 10B may be employed with the alternate cannula 28A, shown in Figure 3. This may be done by either using the alternate reduced cylindrical portion 44B to engage the dispensing cannula plunger 46 or, alternately, by modifying the second alternate plunger 34B so as to eliminate the alternate reduced cylindrical portion 44B. If the alternate reduced cylindrical portion 44B is eliminated, the alternate cylindrical main body 42B serves as the alternate lower end 38B of the second alternate plunger 34B which is engagable with the dispensing cannula plunger 46. While the invention has been described with a certain degree of particularity, it is manifest that many changes may be made in the details of construction and the arrangement of components without departing from the scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for purposes of exemplification, but is to be limited only by the scope of the attached claim or claims.

Claims: A method of applying gutta percha (12) to a carrier (14) comprising: (a) inserting a cannula (28) (28A) (28B) filled with gutta percha through a barrel cavity (24) (24B) in a barrel (16) of a syringe-type device (10) (10A) (10B) until an upper open end (30) (30B) of the cannula is secured in the barrel cavity of the syringe-type device and an opposite, lower, open end of the cannula opens externally of the device; (b) heating the gutta percha in order to thermally increase the plasticity of the normally viscous gutta percha, which step can be accomplished either before or after (a); (c) inserting a plunger (34) (34A) (34B) into the barrel cavity until it touches the gutta percha; (d) inserting the carrier into the lower open end of the cannula; and (e) pushing the carrier and gutta percha out of the lower open end of the cannula by means of the plunger. A method according to claim 1 wherein the lower open end of the cannula (28) (28A) is adjacent the dispensing end (20) of the syringe-type device when the upper open end is secured in the barrel cavity (24). A method according to claim 1 in which the upper open end of the cannula (28B) is secured at the dispensing end (20B) of the device and the lower open end extends outward from the dispensing end. A method according to any preceding claim wherein the cannula (28A) is provided with its own dispensing cannula plunger (46). A method according to any preceding claim wherein the cannula (28) (28A) is inserted into the barrel cavity (24) by means of an opening (26) provided in the barrel. A device (10) (10A) (10B) for applying gutta percha (12) to a carrier (14) comprising: a barrel (16) provided with a barrel cavity (24) (24B) communicating between a plunger insertion end (18) (18B) and an opposite dispensing end (20) (20B); a plunger (34) (34A) (34B) movable within the body cavity, means (44) (44B) being provided at the lower end of the plunger for dispensing the carrier and gutta percha from the device; and characterized by means (32) for retaining a cannula (28) (28A) (28B) which is pre-filled with gutta percha in the barrel cavity so that a carrier (14) is insertable into the cannula when the gutta percha is heated in order to thermally increase the plasticity of the normally viscous gutta percha. A device (10) (10A) (10B) according to claim 6 wherein finger tabs (22) (22B) are provided on the plunger insertion end (18) (18B) on either side of the barrel (16) which extend outward therefrom for gripping the barrel. A device (10) (10A) (10B) according to claim 6 or 7 further comprising an insulating sleeve (21) (21B) being provided externally on the barrel (16) adjacent the plunger insertion end (18) (18B). A device (10) (10A) (10B) according to claim 6, 7 or 8 wherein the barrel (16) is provided with an opening (26) which communicates with the barrel cavity (24) and through which a cannula (28) may be inserted into the barrel cavity. A device (10) (10A) (10B) according to claim 6, 7, 8 or 9 wherein the means for retaining a cannula (28) (28A) (28B) within the barrel cavity (24) (24B) comprises a reduced diameter section (32) (32B) of the barrel cavity which mates with an upper lip (30) (30B) on the cannula. A device (10B) according to claims 10 wherein the reduced diameter section (32B) of the barrel (16) forms the opening at the dispensing end (20B) of the device, so that a cannula (28B) retained in the device extends outwardly therefrom. A device (10) (10A) (10B) according to any of claims 6 to 11 wherein a ring (40) (40B) is provided at the upper end of the plunger (34) (34A) (34B) for gripping it the plunger. A device (10) (10B) according to any of claims 6 to 12 wherein the means for dispensing a carrier (14) and gutta percha (12) from the device comprises a reduced diameter section (44) (44B) at the lower end of the plunger (34) (34B), the reduced diameter section being movable through a cannula (28) (28B) retained in the device. A device (10A) according to any of claims 6 to 12 wherein the means for dispensing a carrier (14) and gutta percha (12) from the device comprises a cylindrical main body (42) of the plunger (34A) which engages a dispensing cannula plunger (46) provided on a cannula (28A) so that the dispensing cannula plunger moves through the cannula. A device (10) (10A) (10B) according to any of claims 6 to 14 constructed of material capable of withstanding heating of the gutta percha (12) contained within a cannula (28) (28A) (28B). A device (10) (10A) (10B) according to any of claims 6 to 15 wherein the cannula (28) (28A) (28B) is pre-filled with a single application of gutta percha (12) in order to prevent cross contamination of carriers (14).

Inventors: JOHNSON WILIAM B, JOHNSON, WILIAM B.
Applicants: TULSA DENTAL PRODUCTS INC, TULSA DENTAL PRODUCTS INC.
Application year: 1994
Main classification: A61C5
IPC codes: A61C5, A61C13